| The development and application of nuclear power and ionizing radiation make it necessary to estimate the radiation risk quantificationally. It is a problem that the public are concerned about and a great challenge to radiation medicine, radiation dosimetry and radiation protection. Recently, radiation accident often occurs with widely uses of radioactive materials and radiation sources. Under the circumstances, it is necessary to carry out dose reconstruction for the exposed victims. Furthermore, dose reconstruction is of great importance in radiation epidemiological studies. In dose reconstruction, the direct measurement of biological sample from human body is the most intuitionistic. At present, the direct measurement includes bio-dosimetry methods (chromosome aberration analysis in peripheral human lymphocytes, micronucleus determination and FISH, etc) and electron paramagnetic resonance (EPR), a bio-physics method to measure the lone-lived radicals in human calcified tissues (tooth, bone, etc).Electron paramagnetic resonance is also called electron spin resonance (ESR). EPR-related dose reconstructions are based on the assessment of radiation-induced radicals in biological samples (tooth, bone, nail and hair). It is sensitive and specific. The radical concentration increases linearly with dose from several dozen mGy to above 100 Gy in the exposed samples. EPR dosimetry became subject of increasing interest during the past decade and was developed rapidly. It has been widely used to dose estimation at radiation and nuclear accidents and of the population living in radioactive contaminated areas.Among the biological samples used in EPR dose reconstruction, tooth enamel has much better dose response and lower measurement limit. The most stable... |
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